BrightStarStamp

class lsst.meas.algorithms.BrightStarStamp(stamp_im: MaskedImageF, gaiaGMag: float, gaiaId: int, position: Point2I, archive_element: Persistable | None = None, annularFlux: float | None = None, minValidAnnulusFraction: float = 0.0, validAnnulusFraction: float | None = None, optimalInnerRadius: int | None = None, optimalOuterRadius: int | None = None)

Bases: AbstractStamp

Single stamp centered on a bright star, normalized by its annularFlux.

Parameters:

stamp_imMaskedImage

Pixel data for this postage stamp

gaiaGMagfloat

Gaia G magnitude for the object in this stamp

gaiaIdint

Gaia object identifier

positionPoint2I

Origin of the stamps in its origin exposure (pixels)

archive_elementPersistable or None, optional

Archive element (e.g. Transform or WCS) associated with this stamp.

annularFluxfloat or None, optional

Flux in an annulus around the object

Attributes Summary

annularFlux
archive_element
minValidAnnulusFraction
optimalInnerRadius
optimalOuterRadius
validAnnulusFraction

Methods Summary

factory(stamp_im, metadata, idx[, ...])	This method is needed to service the FITS reader.
measureAndNormalize(annulus[, statsControl, ...])	Compute "annularFlux", the integrated flux within an annulus around an object's center, and normalize it.

Attributes Documentation

annularFlux: float | None = None

archive_element: Persistable | None = None

minValidAnnulusFraction: float = 0.0

optimalInnerRadius: int | None = None

optimalOuterRadius: int | None = None

validAnnulusFraction: float | None = None

Methods Documentation

classmethod factory(stamp_im, metadata, idx, archive_element=None, minValidAnnulusFraction=0.0)

This method is needed to service the FITS reader. We need a standard interface to construct objects like this. Parameters needed to construct this object are passed in via a metadata dictionary and then passed to the constructor of this class. This particular factory method requires keys: G_MAGS, GAIA_IDS, and ANNULAR_FLUXES. They should each point to lists of values.

Parameters:

stamp_imMaskedImage

Pixel data to pass to the constructor

metadatadict

Dictionary containing the information needed by the constructor.

idxint

Index into the lists in metadata

archive_elementPersistable or None, optional

Archive element (e.g. Transform or WCS) associated with this stamp.

minValidAnnulusFractionfloat, optional

The fraction of valid pixels within the normalization annulus of a star.

Returns:

brightstarstampBrightStarStamp

An instance of this class

measureAndNormalize(annulus: ~lsst.afw.geom.SpanSet, statsControl: ~lsst.afw.math.StatisticsControl = <lsst.afw.math.StatisticsControl object>, statsFlag: ~lsst.afw.math.Property = <Property.MEAN: 4>, badMaskPlanes: ~collections.abc.Collection[str] = ('BAD', 'SAT', 'NO_DATA'))

Compute “annularFlux”, the integrated flux within an annulus around an object’s center, and normalize it.

Since the center of bright stars are saturated and/or heavily affected by ghosts, we measure their flux in an annulus with a large enough inner radius to avoid the most severe ghosts and contain enough non-saturated pixels.

Parameters:

annulusSpanSet

SpanSet containing the annulus to use for normalization.

statsControlStatisticsControl, optional

StatisticsControl to be used when computing flux over all pixels within the annulus.

statsFlagProperty, optional

statsFlag to be passed on to afwMath.makeStatistics to compute annularFlux. Defaults to a simple MEAN.

badMaskPlanescollections.abc.Collection [str]

Collection of mask planes to ignore when computing annularFlux.